The invention relates to reciprocating piston engines, and in particular to coupling arrangements for interconnecting a gudgeon pin and a crankshaft journal of such an engine. The invention is applicable to reciprocating piston combustion engines and compression engines and it will be convenient to hereinafter describe the invention in relation to that exemplary application, although it should be appreciated that the invention is not limited to the application.
Conventional reciprocating piston engines are generally manufactured in two and four stroke designs. A single piston is housed within each cylinder, the piston being connected from a central piston gudgeon pin to a single bearing crankshaft journal by a single solid center mounted connecting rod. After combustion has taken place in the combustion chamber of the piston, the energy derived from the expansion of the combustible material forces the piston to travel along the length of the cylinder away from the combustion chamber. This translational movement is transferred via the connecting rod to the crankshaft journal and is transformed into a rotational movement as the crankshaft is driven around its longitudinal axis. As the crankshaft completes each revolution, the connecting rod interconnecting the crankshaft journal and the gudgeon pin forces the piston back along the length of the cylinder towards the combustion chamber, where combustion once again takes place and the cycle is repeated.
Conventional engines of this type are arranged so that the maximum combustive pressure within the cylinder is generated when the piston is at top dead center and the crankshaft journal is at a corresponding top center position, that is to say, at a position closest to the cylinder combustion chamber. The resultant effect of this arrangement is that immediately following ignition at or slightly after the top center position of the crankshaft, the downward travel of the piston in the cylinder rapidly causes the enlargement of the volume of the cylinder above the upper surface of the piston. A rapid drop in combustion pressure is thus created and there is a corresponding rapid reduction in the force applied to the piston, and hence to the crankshaft journal for rotation of the crankshaft.
The applicant has observed that such an arrangement inefficiently converts energy from the combustion of gases in the combustion chamber to a motive force for turning the crankshaft. There exists a need to create a more efficient reciprocating piston engine where more power can be derived from the same amount of combustible material or, alternatively, a lesser amount of combustible material may be used to achieve the same amount of power.